Q: Is the herb senna safe to take as a laxative? What about Swiss Kriss?
A: It’s okay to take senna laxatives for occasional constipation, when used as directed. The labels warn not to take them for more than a week, but we advise limiting them to a few days.
Senna, from the leaves of the Senna alexandrina shrub, has been used as an herbal digestive remedy for centuries. Its key components are called sennosides (senna glycosides), which usually produce a bowel movement in 6 to 12 hours. Though it is sold as an herbal supplement, senna is also FDA-approved for short-term use as a stimulant laxative and is found in OTC products such as Senokot and Ex-Lax.
Senna is just one of several stimulant laxatives, which increase contractions of intestinal muscles to move stool along. (Another stimulant is bisacodyl, found in Dulcolax, for instance, which may have fewer side effects.) Many people choose such laxatives because they act quickly, but they can cause cramping and diarrhea. And taken longer term, they may impair bowel function and cause laxative dependency. The most serious concern about excessive use of stimulant laxatives is that they can cause a dangerous loss of electrolytes (including potassium).
Senna and other herbal laxatives are sometimes promoted as diet aids. But this is a dangerous way to lose weight and won’t reduce body fat—and the pounds will quickly return when you stop taking the laxative.
Swiss Kriss, a popular century-old herbal laxative sold alongside other OTC laxatives, carries the claim that it’s “100% natural and contains no harsh synthetic drugs.” It’s really no more natural than Ex-Lax, since sennosides are the only active ingredient listed on the label. Swiss Kriss also contains anise and caraway seeds, strawberry and peach leaves, peppermint oil, and other herbs, which are supposed to reduce gas and have other benefits. But there’s no evidence that it works better or more gently than simple senna laxatives.
Bottom line: It’s best to not rely on any type of laxative, especially a stimulant one. If you have recurrent or chronic constipation, consult your health care provider to make sure there’s no underlying problem (such as low thyroid) and to discuss “bowel-friendly” lifestyle changes. That includes a high-fiber diet (more fruits, whole grains, beans, and vegetables, along with increased fluid intake) and regular exercise (such as daily walking). If you do need a laxative on an ongoing basis, bulk-forming types containing psyllium (such as Metamucil) or other kinds of fiber are the only good choices. For short-term use, polyethylene glycol (such as Miralax) is gentler than stimulant types. You can also try this self-help technique.